The bastions or towers are perfectly safe as they are maintained in good condition. Last year I visited one and was a nice adventure.
We don't have heavy rains here and the books are protected by a roof. And no one is stealing them as there's video surveillance and it's free to borrow them 😀
Really? No heavy rains there? Here we experienced most of the time and things even under the roof as long as they're put in the side might get wet due to rain brought by the air.
Ah okay, cctv will know it who will get the books.